The art of manufacture of corrugated cartons and the like entails the operation of cutting sections of the corrugated web as it discharges from the corrugating machine to predetermined lengths in a continuous process. For this purpose, machines having rotary cutting elements or knives which are programmed to properly shear the web as it moves through the machine continuously are utilized.
It has been found that the rotary knives or shears of the cutter operate more advantageously when the cutter or blade is mounted helically upon the rotary cutter. The helical configuration permits the cutting blade to move progressively through the web rather than making a straight through vertical cut which is accompanied by a high pressure resistance from the web instantaneously and consequence stress upon the machine.
The advantage of the helical rotary cutter was set forth in applicant's U.S. Pat. No. 3,380,328 issued Apr. 30, 1968 covering a single blade helical cutter.
In his U.S. Pat. No. 4,183,271, applicant describes and claims a web shearing machine employing a plurality of cutters arranged in pairs so that two helical cutters work in conjunction with each other as separate set of cutters with their obvious advantages.
The advantages of the helical cutters over the straight knife are set forth in substantial detail in applicant's U.S. Pat. No. 4,183,271.
While applicant has solved most of the existing problems in rotary web shearing machines, there remains one problem particularly associated with the helical blades. This is brought about by the necessity of maintaining the proper relationship between the cutting edges of the blades with special regard to clearance which problem is aggravated by wear on the blades, necessitating frequent shutdown of the machine to adjust the blades with respect to one another. This is an operation which must be performed during intervals of two weeks to a month depending upon the operation and requires several hours to perform which necessitates shutting down the whole production line for that length of time.
I have invented a device which provides for movement of at least one of the shafts carrying a helical cutting blade axially while the shaft is in motion and the companion blade remains in the same horizontal position, thus bringing the blades in closer proximity to each other and effecting the necessary cutting relationship between the blades and eliminating the necessity of shutting down the machine to effect this. Of course I may move both blades axially with respect to each other to effect even closer proximity. I may also effect this operation when the blades are stationary, especially when the machine is shut down for other reasons.